If it feels like it is starting to loose power do a compression check and if it is good you probably just need a good tune up. My speedo reads 164,000 miles and the last 104,000 has been with 31" tall tires. My power still feels good, it's not a power house but it still feels as strong as always. I have an open K&N filter with a 2 1/4" exhaust and a turbo muffler.

Dennis

95 Sportage, gone but not forgotten.
98 Jeep TJ, 4" Zone springs with RC Long arms, Ford 8.8", 4.56 gears & Detroit locker rear, D30, 4.56 & Detroit Trutrack front.